I just purchased a classic, 1986 Aspencade with 55,000 miles.
I'm the 3rd owner, the last owner had the bike for 15 years and kept perfect maintenance records of every oil change and all major repairs including the Stator, done 4000 miles ago.
The original molex plug was still on the 3 yellow wires, but they were spliced and soldered just above the plug. I thought the plug was the "problem" so I cut it out and used some good quality waterproof butt connectors to connect the wires and eliminate the plug. I'm getting over 6 volts at each yellow wire.

I've owned over a dozen bikes in the past, but never a Wing. I'm sure it will be great for some 2-up riding with my wife.

the correct method to check the stator output requires checking the 3 yellow wires disconnected from the mc,which in your case since you have already hardwired to plug can be done by disconnecting the regulator plug and checking the ac output on the ac scale of your meter A-B,A-C,B-C output should all be in the 40-70 vac range

feel free to check in the electrical section for other pertinent upgrades you should do to prptect your system's weak links

regular oil changes, keep the tire pressure up, watch the charging AMPS as the stators are the weak link (Poorboy has fixed that, though), pack what cha' need and you and your wife put some (s)miles on.......

enjoying the view from the saddle....... due mainly to the people and information found within this site